I don’t want to carry a proper bike lock on a brevet for the few times I am off the bike, but I do feel a bit nervous leaving an expensive bike on the street unlocked while I’m inside a cafe getting food/drink and using the washroom. I decided to use one of these small cable locks folks generally employed for locking luggage or ski/snowboards. They are cheap and light with a combination so there are no keys to lose. They won’t stop a professional bike thief, but they will prevent someone from impulsively riding away with your trusty stead. Since the lock is small and the cable so thin I can stealth lock my bike so the thief doesn’t realize it’s locked and hopefully falls flat on his face when he tries to ride away.

At least you can't easily ride away...

This solution might also be useful for the bike commuter who can store their bike inside at work and might want to stop for some milk or a coffee on the way home. No point in bothering with a heavy lock for a 3min stop – in most neighbourhoods anyways!